In the manufacture of multicolor printed web material such as carpets, multiple imprints on the same portion are made with different colored dyes. Care must be taken that the respective patterns are properly aligned, have the correct color and that the printing dyes are applied in the precise amount for optimum printing without blurring of the composite pattern.
The U.S. Pat. No. 3,974,766 to Zimmer is exemplary of a system for printing a composite pattern on a web carpet while using sensing devices with a memory unit to provide control over registration. The Zimmer system relies upon web sensing devices which identify specific web areas where printing may be required. The Zimmer system is complex and does not provide automatic control over the quality of the printing such as may be caused by variations in the dyes, squeegee pressure and the like.
When, for example, a number of dye printing stations are employed in a large carpet printing system such as described in the U.S. Pat. No. 3,374,731 to Thorne, it is necessary to check that each print strike is properly aligned with the appropriate squeegee or pump pressure for the screens. In practice, the initial feet of a blank carpet are employed to adjust the printing stations. As a result, the front segment of a carpet frequently has inferior quality printing and is likely to be unusable.
In practical carpet printing operations, frequent start-ups using different patterns occur, with as many as three start-ups per day being common. When the total carpet spoilage is considered as a result of frequent start-ups, the financial loss is significant.